Comparison of an Immunohistochemical and a Histochemical Stain in Detection of Copper in Rat Tissues

Abstract

Routine pathological diagnosis of hepatic copper (Cu) has traditionally depended upon histochemical stains such as rubeanic acid, rhodanine and orcein (1). The sensitivity and specificity of these stains are often unknown. In recent years, metallothionein (MT) has been used in immunohistochemical techniques, to indicate presence and distribution of heavy metals, in particular Cu, within biological tissues (2,3). Metallothionein (MT) is a low molecular weight (6000 D), cysteine-rich, cytoplasmic protein, with a high affinity for cadmium (Cd), Cu, zinc (Zn) and other heavy metals. It is thought to be involved in cellular detoxification due to metal sequestration (4). The purpose of this study was to compare MT immunostaining with rubeanic acid staining of Cu in normal and Cu-loaded rat tissues.